Enhanced expression of stress protein 70 in the brains of goldfish, Carassius auratus, reared with bluegills, Lepomis macrochirus

Induction of stress protein (HSP70) was studied in goldfish (Carassius aura tus) reared with bluegills (Lepomis macrochirus), a predator of small fish. HSP70 was identified by Western blotting and quantified by optical density after SDS-PAGE. The expression of HSP70 was significantly enhanced in the brains of goldfish reared with bluegills for 6 and 12 h in a single tank. T he hepatopancreas and the kidney were not affected by the treatment. When g oldfish were separated from bluegills with a partition net (1 x 1 cm mesh s ize), this protein also increased in the brains after 6 h but then returned to the control level after 12 h. When the goldfish and bluegills were kept in separate tanks and were not able to see each other but were connected b y circulating water, HSP70 levels in the goldfish were unaffected. Immunohi stochemical observations indicated that an anti-HSP70 antibody was found to react predominantly with the optic and vagal lobes of the brains. These re sults suggest that visual perception plays a primary role in enhancement of HSP70 expression in the goldfish reared with bluegills.